The trend, requirement and development of DC technologies for medium and low voltage DC grids

DC technologies have already been widely used in high voltage transmission networks for the large transfer capacity and flexible control. DC technologies show also advantages over conventional AC technologies in low voltage microgrids and in medium voltage networks for reducing losses, fulfilling the increasing load demands, and integrating renewable power generation to the distribution networks. In addition, transport electrification brings new opportunities and challenges for using DC technologies. With the increase of reliability and reduction of costs of power electronic converters, medium voltage and low voltage DC (MV/LVDC) will play more and more important roles in modern power systems. The technologies aims to reduce operation costs, increase capacity, enhance reliability and increase power quality.
MV/LVDC have been used for various applications, which include smart building (also smart office/classroom), distributed energy sources (wind, solar, storage), industrial and commercial loads (motor drives and data centers), transport electrification (electric vehicles, shipboard, rail aircrafts), offshore platform power supply, offshore renewable collection, and distribution networks.
However, these applications are designed at different voltages to meet their specific requirements individually. So far, standardization has not been put into practice in order to facilitate the development of components and devices from various manufacturers and contribute to the wider applications of DC technologies.
The DC voltage is constrained by the insulation capability of the existing cables, and acceptable levels of audible noise in dry weather as well as electric field and space charge current at ground level. The maximum transfer capacity is influenced by the DC voltage. Thus, The factors influencing the DC voltages and system operation needed to be surveyed and analyzed, which include voltage standards, configurations of converters, protection strategies, control strategies, dispatching and restoration for hybrid AC/DC voltage, optimal economical operation, and system reliability.
This Special Session will cover trend of MV/LV DC grid development, relevant technology requirements and DC voltage standardization. Experience from existing MV/LVDC technologies, and factors affecting DC grids operation will also be included for the benefits of future developments.

Session Chair:

Jun Liang is a full Professor at Cardiff University, United Kingdom. He has over 26 years’ experience in DC technology, power electronic converter control, power system stability operation and control. He currently leads a research group in power electronics and HVDC for renewable power generation and transmission. He has obtained research funding over £10 M in 18 projects. In particular, he is the Coordinator and Scientist-in-Charge of two European Commission Marie-Curie Action ITN projects: MEDOW (€3.9M) and InnoDC (€3.9M). He has published over 155 papers including 72 journal papers, 1 book in IEEE/Wiley, and 3 book chapters in Woodhead Publishing. H-index is 28. He actively promotes the technology of voltage source converter (VSC) based HVDC and the operation and control of Multiterminal VSC-HVDC grids for offshore wind. He is the Chair of UK&Ireland Chapter of IEEE Power Electronics Society, a committee member of CIGRE Working Groups B4-58, 60, 62 and 72, the Technical Secretary of the CIGRE WG B4-60 and C6/B4.37, an Editorial Board Member of CSEE JPES, a Guest Editor of IEEE Transaction on Power Delivery, a Chair of the European HVDC PhD Colloquium, and technical committee members of several international Conferences. He has been appointed as an Adjunct Professor at Changsha University of Science and Technology, North China Electric Power University and Northeast Electric Power University. Personal web: http://junliang.strikingly.com/

Speakers:

Jun Liang, Cardiff University, United Kingdom

Kai Strunz and Bernardo Severino, TU Berlin, Germany

Igor Cvetkovic, Virginia Tech

Kazuto Yukita, Aichi Institute of Technology, Japan and Keiichi Hirose, NEDO (New Energy and Industrial Technology Development Organization), Japan